The present invention relates to the technical field of electrical connection systems of electrical devices for vehicles, used at high temperature, such as for example spark plugs, actuators or measurement sensors.
The object of the invention relates more particularly to an electrical connection system for an electrical device for measuring exhaust gas physical parameters or components such as temperature, mass of particles, gaseous composition, etc.
The object of the invention finds a particularly advantageous application in the field of measuring soot in exhaust gases.
In the state of the art, diverse embodiments are known of a measurement device for exhaust gases. For example, U.S. Pat. No. 5,246,562 describes a device including, within a tubular metal body, a detector embodied in the form of an elongated dielectric component having a distal part provided with at least one electrode constituting a measurement cell. This measurement cell is electrically connected to electrical contact pads provided in the proximal part of the detector. This device also includes a system for electrically connecting the detector to an electrical wiring harness. Such a connection system includes two dielectric half-shells assembled face-to-face, between which is inserted the proximal part of the detector. Fingers for making electrical contact with the pads are interposed between at least one half-shell and the detector and are electrically connected to the wiring harness. The two half-shells are held in position by means of a spring collar.
In general, it should be noted that such an electrical device mounted on a vehicle is subjected to mechanical vibrations. Hence, one of the major drawbacks of such a device relates to the difficulty of establishing and maintaining over time an effective electrical connection between the detector and the electrical contact fingers. To attempt to correct this flaw, U.S. Pat. No. 6,878,252 proposes to create an assembly of the half-shells by providing protuberances and cavities on each of them, mutually cooperating so as to avoid relative motion between the two half-shells that would be liable to spoil the electrical connection between the contact pads and the electrical fingers.
This technical solution requires the manufacture of shells having relatively complex shapes. Further, such a device has considerable bulk, which constitutes a disadvantage in many applications.
The present invention therefore aims to remedy the disadvantages of the state of the art by proposing a new electrical connection system for vehicles, used at high temperature, having a simple design and limited bulk, designed to reliably provide an electrical connection with the electrode of the dielectric component, regardless of the vibratory loads to which such an electrical device is subjected.
To attain such an objective, the electrical connection system for vehicles between electrical contact pads arranged on the proximal part of an elongated dielectric component and an electrical wiring harness comprises:                two dielectric half-shells assembled face-to-face so as to have on one side a distal part and on the opposite side a proximal part, the proximal part of the component being inserted between the two half-shells on the side of the distal part,        fingers for electrical contact with the pads, interposed between at least one half-shell and the component, and electrically connected to the wiring harness,        a spring collar surrounding the half-shells to ensure that they are held in position. According to the invention:        the half-shells include, at the proximal part, a pivot such that the half-shells open angularly relative to one another in the direction of the distal part, the spring collar surrounding the half-shells at the proximal part to hold them in the open angular position,        the half-shells together include externally, at the distal part, a bearing surface for a tubular body bringing the two half-shells together to ensure electrical contact between the contact fingers and the pads.        
According to one feature of the invention, the spring collar is assembled on the half-shells such that the half-shells and the spring collar are assembled inside the tubular body.
According to a preferred embodiment, the spring collar is assembled in a rebate provided externally on the half-shells.
Advantageously, the half-shells together delimit, at the proximal part, a contact area constituting the pivot.
According to one variation in implementation, each contact finger includes at least one spring portion kept under tension by a half-shell.
According to another variation of implementation, the contact fingers each include at least one ductile portion.
For example, the half-shells together delimit a recess for receiving the proximal part of the component, having a stop surface for said component.
According to one variation of implementation, the contact pads are electrically connected to at least one electrode borne by the detector.
For example, the contact fingers extend outside the half-shells, on the side of the proximal part, to allow their connection to the wiring harness.
According to one advantageous embodiment, the half-shells have, at their distal part, a chamfer that assists insertion into the tubular body.
Another object of the invention is to propose a system, conforming to the invention, for electrical connection between an electrical wiring harness and an elongated dielectric component constituting a detector, particularly of soot in exhaust gases.
Another object of the invention is to propose an electrical device for a vehicle that includes a system, conforming to the invention, for electrical connection between a wiring harness and a spark plug.
Various other features appear from the description given below with reference to the appended drawings which show, by way of non-limiting examples, embodiments of the object of the invention.